Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0019163 (hepatitis B)
 38,309 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Epidemiology shows a clear correlation between chronic infection with the hepatitis B virus (HBV) and development of hepatocellular carcinoma (HCC). The potential role of the transactivating hepatitis B virus X protein (HBx) in transformation by HBV is controversial. Here we report that HBx suppresses transformation of primary rat embryo fibroblasts (REFs). Cooperating oncogenes like c-Ha-ras and c-myc transform REF very efficiently but cotransfection with HBx suppressed transformation of REFs down to 5%. Similarly, transfection of HBx together with the cooperating oncogenes Ha-ras and SV40 LTAg or c-Ha-ras and mutant p53 reduced the number of foci to 13%. Comparable results were obtained with HBx in the context of the whole HBV. Suppression of focus formation in REF could be partly relieved by cotransfection of apoptosis inhibitors Bcl-2 or E1B. However, cotransfection of apoptosis inhibitors crmA and p35 did not influence the proapoptotic functions of HBx. Thus, HBx may specifically activate the Bcl-2 sensitive pathway leading to apoptosis. Experiments with 13 HBx linker scanning mutants revealed that the domains necessary for HBx dependent transactivation overlap with the domains needed for the apoptotic/growth arrest functions of HBx.
 ...
PMID:Induction of apoptosis by the transactivating domains of the hepatitis B virus X gene leads to suppression of oncogenic transformation of primary rat embryo fibroblasts. 1071 5

Replication-selective adenovirus has been reported to kill tumor cells and hold promise for cancer therapy. In this study, we constructed an E1B M(r) 55000-deleted adenovirus, designated Ad5WS1, and examined its cytolytic effect on human hepatocellular carcinoma (HCC) cell lines with various p53 status. The results show that Ad5WS1 lysed HCC cells lacking p53 transcription activity. However, this effect was not observed in cells harboring functional p53. Because loss of p53 transcription activity can be induced by binding to hepatitis B virus X protein (HBx), we generated HBx stable transfectants from Chang liver cells and examined their susceptibility to Ad5WS1-induced cytolysis. Expression of HBx in Chang liver cells changed the location of p53 from the nucleus to the cytoplasm, which mostly coincided with the location of HBx in the cytoplasm. Disruption of p53 transcription activity by HBx in Chang liver cells rendered them susceptible to infection with Ad5WS1. Furthermore, Ad5WS1 exerted antitumor effect, especially when combined with chemotherapeutic agent cisplatin, in BALB/c mice bearing HBx-expressing HCC. Our results suggest that E1B M(r) 55000-deleted adenovirus may have therapeutic potential for the treatment of HCC with loss of p53 transcription activity or with HBx expression.
 ...
PMID:Hepatitis B virus X protein sensitizes hepatocellular carcinoma cells to cytolysis induced by E1B-deleted adenovirus through the disruption of p53 function. 1253 86

The latent membrane protein-1 (LMP1) of Epstein-Barr Virus (EBV), saimiri transformation protein (STP) of Herpesvirus saimiri (HVS), and K1 protein of Kaposi's sarcoma-associated herpesvirus (KSHV) are potent gammaherpesvirus oncogenes. To study the possible effects of double viral infection, we investigated the effects of oncogenic early proteins of DNA viruses E1A and E1B (adenovirus-5), E6 and E7 (human papillomavirus-16), HBx (hepatitis B virus), Tag (SV40), and gammaherpesviral oncogene during co-infection in human B-lymphoma (Ramos) and human T-cell leukemia (Jurkat) cell lines. HBx transactivated the promoters of LMP1, STP, and K1 the most, by about six-, three-, and twofold, respectively. Analyses of site-directed mutation and the heterologous promoter system showed that HBx activated the promoter activity of these genes via the NF-kappaB site. These results suggest that HBV (HBx) infection of cells previously infected by gammaherpesviruses transactivates their oncogenes, resulting in possible virus-related disease pathogenesis.
 ...
PMID:Transcriptional activation of gammaherpesviral oncogene promoters by the hepatitis B viral X protein (HBx). 1506 83

The tumor suppressor gene TP53, encoding the p53 protein, has its gene locus on the short arm of chromosome 17 p13.1 (1,2). p53 has been denoted "guardian of the genome" (3) owing to its essential cellular functions in apoptosis control, cell-cycle control, chromosomal segregation, gene transcription, and genomic stability (4). The gene encodes a protein of 393 amino acids (5). The tertiary structure of the p53 protein is known to a relatively large extent; the DNA binding region has been localized to amino acids 102 to 292. Murine double minute-2 (MDM2) binds to the amino terminal of the p53 protein and is a negative regulator of p53 (6). p53 is normally activated by ultraviolet (UV)-light, radiation, cytostatics, and carcinogens. The activation by these may involve interaction with the ataxia telangiectasia gene (ATM). The p53 gene can be inactivated by somatic or germ-line mutations. Somatic mutations in the p53 gene is the most common genetic abnormality so far described in human cancer (7). Patients with germ-line p53 mutation's are part of the Li-Fraumeni syndrome. These patients have an increased risk of developing adrenocortical, breast, gastrointestinal tract, and lung carcinoma, as well as soft-tissue sarcoma and malignant melanoma (8,9). Studies on mice have revealed that induced deficiency of both alleles of the p53 gene is associated within an increased risk of lymphomas and sarcomas (10). p53 can also be inactivated by certain viral oncoproteins, such as human papilloma virus protein E6, SV40 large T-antigen, hepatitis B viral X protein, and adenovirus protein E1B (4).
 ...
PMID:Analysis of the p53 Status of Tumors : An Overview of Methods. 2137 38